The present invention relates generally to surgical tools and, more particularly, to various wrist mechanisms in surgical tools for performing robotic surgery.
Advances in minimally invasive surgical technology could dramatically increase the number of surgeries performed in a minimally invasive manner. Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. The average length of a hospital stay for a standard surgery may also be shortened significantly using minimally invasive surgical techniques. Thus, an increased adoption of minimally invasive techniques could save millions of hospital days, and millions of dollars annually in hospital residency costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work may also be reduced with minimally invasive surgery.
The most common form of minimally invasive surgery may be endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient""s abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately xc2xd inch) incisions to provide entry ports for laparoscopic surgical instruments. The laparoscopic surgical instruments generally include a laparoscope (for viewing the surgical field) and working tools. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by an extension tube. As used herein, the term xe2x80x9cend effectorxe2x80x9d means the actual working part of the surgical instrument and can include clamps, graspers, scissors, staplers, and needle holders, for example. To perform surgical procedures, the surgeon passes these working tools or instruments through the cannula sleeves to an internal surgical site and manipulates them from outside the abdomen. The surgeon monitors the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy and the like.
There are many disadvantages relating to current minimally invasive surgical (MIS) technology. For example, existing MIS instruments deny the surgeon the flexibility of tool placement found in open surgery. Most current laparoscopic tools have rigid shafts, so that it can be difficult to approach the worksite through the small incision. Additionally, the length and construction of many endoscopic instruments reduces the surgeon""s ability to feel forces exerted by tissues and organs on the end effector of the associated tool. The lack of dexterity and sensitivity of endoscopic tools is a major impediment to the expansion of minimally invasive surgery.
Minimally invasive telesurgical robotic systems are being developed to increase a surgeon""s dexterity when working within an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location. In a telesurgery system, the surgeon is often provided with an image of the surgical site at a computer workstation. While viewing a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices of the workstation. The master controls the motion of a servomechanically operated surgical instrument. During the surgical procedure, the telesurgical system can provide mechanical actuation and control of a variety of surgical instruments or tools having end effectors such as, e.g., tissue graspers, needle drivers, or the like, that perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, or dissecting tissue, or the like, in response to manipulation of the master control devices.
Some surgical tools employ a roll-pitch-yaw mechanism for providing three degrees of rotational movement to an end effector around three perpendicular axes. The pitch and yaw rotations are typically provided by a wrist mechanism coupled between a shaft of the tool and an end effector, and the roll rotation is typically provided by rotation of the shaft. At about 90xc2x0 pitch, the yaw and roll rotational movements overlap, resulting in the loss of one degree of rotational movement, referred to as a singularity.
The present invention is directed to alternative embodiments of a tool having a wrist mechanism that provides pitch and yaw rotation in such a way that the tool has no singularity in roll, pitch, and yaw. In one preferred embodiment, a wrist mechanism includes a plurality of disks or vertebrae stacked or coupled in series. Typically the most proximal vertebrae or disk of the stack is coupled to a proximal end member segment, such as the working end of a tool or instrument shaft; and the most distal vertebrae or disk is coupled to a distal end member segment, such as an end-effector or end-effector support member. Each disk is configured to rotate in at least one degree of freedom or DOF (e.g., in pitch or in yaw) with respect to each neighboring disk or end member.
In general, in the discussion herein, the term disk or vertebrae may include any proximal or distal end members, unless the context indicates reference to an intermediate segment disposed between the proximal and distal end members. Likewise, the terms disk or vertebrae will be used interchangeably herein to refer to the segment member or segment subassembly, it being understood that the wrist mechanisms having aspects of the invention may include segment members or segment subassemblies of alternative shapes and configurations, which are not necessarily disk-like in general appearance.
Actuation cables or tendon elements are used to manipulate and control movement of the disks, so as to effect movement of the wrist mechanism. The wrist mechanism resembles in some respects tendon-actuated steerable members such as are used in gastroscopes and similar medical instruments. However, multi-disk wrist mechanisms having aspects of the invention may include a number of novel aspects. For example, a wrist embodiment may be positively positionable, and provides that each disk rotates through a positively determinable angle and orientation. For this reason, this embodiment is called a positively positionable multi-disk wrist (PPMD wrist).
In some of the exemplary embodiments having aspects of the invention, each disk is configured to rotate with respect to a neighboring disk by a nonattached contact. As used herein, a nonattached contact refers to a contact that is not attached or joined by a fastener, a pivot pin, or another joining member. The disks maintain contact with each other by, for example, the tension of the actuation cables. The disks are free to separate upon release of the tension of the actuation cables. A nonattached contact may involve rolling and/or sliding between the disks, and/or between a disk and an adjacent distal or proximal wrist portion.
As is described below with respect to particular embodiments, shaped contact surfaces may be included such that nonattached rolling contact may permit pivoting of the adjacent disks, while balancing the amount of cable motion on opposite sides of the disks. In addition, the nonattached contact aspect of the these exemplary embodiments promotes convenient, simplified manufacturing and assembly processes and reduced part count, which is particularly useful in embodiments having a small overall wrist diameter.
It is to be understood that alternative embodiments having aspects of the invention may have one or more adjacent disks pivotally attached to one another and/or to a distal or proximal wrist portion in the same or substantially similar configurations by employing one or more fastener devices such as pins, rivets, bushings and the like.
Additional embodiments are described which achieve a cable-balancing configuration by inclusion of one or more inter-disk struts having radial plugs which engage the adjacent disks (or disk and adjacent proximal or distal wrist portion). Alternative configurations of the intermediate strut and radial plugs may provide a nonattached connection or an attached connection.
In certain embodiments, some of the cables are distal cables that extend from a proximal disk through at least one intermediate disk to a terminal connection to a distal disk. The remaining cables are medial cables that extend from the proximal disk to a terminal connection to a middle disk. The cables are actuated by a cable actuator assembly arranged to move each cable so as to deflect the wrist mechanism. In one exemplary embodiment, the cable actuator assembly may include a gimbaled cable actuator plate. The actuator plate includes a plurality of small radius holes or grooves for receiving the medial cables and a plurality of large radius holes or grooves for receiving the distal cables. The holes or grooves restrain the medial cables to a small radius of motion (e.g., xc2xd R) and the distal cables to a large radius of motion (R), so that the medial cables to the medial disk move a smaller distance (e.g., only half as far) compared to the distal cables to the distal disk, for a given gimbal motion or rotation relative to the particular cable. Note that for alternative embodiments having more than one intermediate cable termination segment, the cable actuator may have a plurality of sets of holes at selected radii (e.g., R, ⅔R, and ⅓R). The wrist embodiments described are particularly suitable for robotic surgical systems, although they may be included in manually operated endoscopic tools.
Embodiments including a cable actuator assembly having aspects of the invention provide to the simultaneous actuation of a substantial plurality of cables, and provide for a predetermined proportionality of motion of a plurality of distinct cable sets. This capability is provided with a simple, inexpensive structure which avoids highly complex control mechanisms. As described further below, for a given total cross-sectional area in each cable set and a given overall disk diameter, a mechanically redundant number of cables permits the cable diameter to be smaller, permits increasing the moment arm or mechanical advantage of the cables, and permits a larger unobstructed longitudinal center lumen along the centerline of the disks. These advantages are particularly useful in wrist members built to achieve the very small overall diameter such as are currently used in endoscopic surgery.
In some embodiments, a grip actuation mechanism is provided for operating a gripping end effector. When cables are used to manipulate the end effector, the grip actuation mechanism may include a grip cable actuator disposed in a tool or instrument proximal base or xe2x80x9cback end.xe2x80x9d The path length of a grip actuation cable may tend to vary in length during bending of the wrist in the event that cable paths do not coincide with the neutral axis. The change in cable path lengths may be accounted for in the back end mechanism used to secure and control the cables. This may be achieved by including a cable tension regulating device in the grip actuation mechanism, so as to decouple the control of the end effector such as grip jaws from the bending of the wrist.
In specific embodiments, the back end mechanism is configured to allow for the replacement of the end effector, the wrist, and the shaft of the surgical instrument with relative ease.
In accordance with an aspect of the present invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end. A wrist member has a proximal portion connected to the working end. An end effector is connected to a distal portion of the wrist member. The wrist member comprises at least three vertebrae connected in series between the working end of the elongate shaft and the end effector. The vertebrae include a proximal vertebra connected to the working end of the elongate shaft and a distal vertebra connected to the end effector.
Each vertebra is pivotable relative to an adjacent vertebra by a pivotal connection, which may employ a nonattached (or alternatively an attached) contact. At least one of the vertebrae is pivotable relative to an adjacent vertebra by a pitch contact around a pitch axis which is nonparallel to the shaft axis. At least one of the vertebrae is pivotable relative to an adjacent vertebra by another contact around a second axis which is nonparallel to the shaft axis and nonparallel to the pitch axis.
In accordance with another aspect of this invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end. A wrist member has a proximal portion or proximal end member connected to the working end, and a distal portion or distal end member connected to an end effector. The wrist member comprises at least three vertebrae connected in series between the working end of the elongate shaft and an end effector.
The vertebrae include a proximal vertebra connected to the working end of the elongate shaft and a distal vertebra connected to the end effector. Each vertebra is pivotable relative to an adjacent vertebra by a pivotable vertebral joint. At least one of the vertebrae is pivotable relative to an adjacent vertebra by a pitch joint around a pitch axis which is nonparallel to the shaft axis. At least one of the vertebrae is pivotable relative to an adjacent vertebra by a yaw joint around a yaw axis which is nonparallel to the shaft axis and perpendicular to the pitch axis. An end effector is connected to a distal portion of the wrist member. A plurality of cables are coupled with the vertebrae to move the vertebrae relative to each other. The plurality of cables include at least one distal cable coupled with the terminating at the distal vertebra and extending proximally to a cable actuator member, and at least one intermediate cable coupled with and terminating at an intermediate vertebra disposed between the proximal vertebra and the distal vertebra and extending to the cable actuator member. The cable actuator member is configured to adjust positions of the vertebrae by moving the distal cable by a distal displacement and the intermediate cable by an intermediate displacement shorter than the distal displacement.
In some embodiments, a ratio of each intermediate displacement to the distal displacement is generally proportional to a ratio of a distance from the proximal vertebra to the intermediate vertebra to which the intermediate cable is connected and a distance from the proximal vertebra to the distal vertebra to which the distal cable is connected.
In accordance with another aspect of the invention, a method of performing minimally invasive endoscopic surgery in a body cavity of a patient comprises introducing an elongate shaft having a working end into the cavity. The elongate shaft has a proximal end and a shaft axis between the working end and the proximal end. A wrist member comprises at least three vertebrae connected in series between the working end of the elongate shaft and the end effector. The vertebrae include a proximal vertebra connected to the working end of the elongate shaft and a distal vertebra connected to the end effector. Each vertebra is pivotable relative to an adjacent vertebra by a pivotal coupling, which may employ a nonattached contact. An end effector is connected to a distal portion of the wrist member. The end effector is positioned by rotating the wrist member to pivot at least one vertebra relative to an adjacent vertebra by a pivotal pitch coupling around a pitch axis which is nonparallel to the shaft axis. The end effector is repositioned by rotating the wrist member to pivot at least one vertebra relative to an adjacent vertebra by another pivotal coupling around a second axis which is nonparallel to the shaft axis and nonparallel to the pitch axis.
In accordance with another aspect of the present invention, a minimally invasive surgical instrument has an end effector which comprises a grip support having a left pivot and a right pivot. A left jaw is rotatable around the left pivot of the grip support and a right jaw is rotatable around the right pivot of the grip support. A left slider pin is attached to the left jaw and spaced from the left pivot pin, and a right slider pin is attached to the right jaw and spaced from the right pivot pin. A slotted member includes a left slider pin slot in which the left slider pin is slidable to move the left jaw between an open position and a closed position, and a right slider pin slot in which the right slider pin is slidable to move the right jaw between an open position and a closed position. A slider pin actuator is movable relative to the slotted member to cause the left slider pin to slide in the left slider pin slot and the right slider pin to slide in the right slider pin slot, to move the left jaw and the right jaw between the open position and the closed position.
In accordance with another aspect of the present invention, a method of performing minimally invasive endoscopic surgery in a body cavity of a patient comprises providing a tool comprising an elongate shaft having a working end coupled with an end effector, a proximal end, and a shaft axis between the working end and the proximal end. The end effector includes a grip support having a left pivot and a right pivot; a left jaw rotatable around the left pivot of the grip support and a right jaw rotatable around the right pivot of the grip support, a left slider pin attached to the left jaw and spaced from the left pivot pin, a right slider pin attached to the right jaw and spaced from the right pivot pin; and a slotted member including a left slider pin slot in which the left slider pin is slidable to move the left jaw between an open position and a closed position, and a right slider pin slot in which the right slider pin is slidable to move the right jaw between an open position and a closed position. The method further comprises introducing the end effector into a surgical site; and moving the left slider pin to slide in the left slider pin slot and the right slider pin to slide in the right slider pin slot, to move the left jaw and the right jaw between the open position and the closed position.
According to another aspect, a medical instrument comprises a base shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end. A segmented wrist member comprises a plurality of spaced-apart segment vertebrae disposed sequentially adjacent to one another along a wrist longitudinal line. The plurality of vertebrae include a proximal vertebra connected to the shaft working end, a distal vertebra supporting an end effector, and at least one intermediate vertebra disposed between the proximal vertebra and the distal vertebra, the at least one intermediate vertebrae being connected to each adjacent vertebra by a pivotally movable segment coupling. Each segment coupling has a coupling axis nonparallel to the wrist longitudinal line. At least two of the coupling axes are non-parallel to one another. At least one of the intermediate vertebrae is a medial vertebra. A plurality of movable tendon elements are disposed generally longitudinally with respect to the shaft and wrist member. The tendon elements each have a proximal portion, and have a distal portion connected to one of the distal vertebra and the medial vertebra so as to pivotally actuate the connected vertebra. At least one of the tendons is connected to the at least one medial vertebra and at least one of the tendons is connected to the distal vertebra. A tendon actuation mechanism is drivingly coupled to the tendons and configured to controllably move at least selected ones of the plurality of tendons so as to pivotally actuate the plurality of connected vertebrae to laterally bend the wrist member with respect to the shaft.
Another aspect is directed to a tendon actuating assembly for a surgical instrument, wherein the instrument includes a shaft-like member having a distal working end for insertion into a patient""s body through an aperture, and wherein the working end includes at least one distal moveable member arranged to be actuated by at least one of a plurality of movable tendon element. The actuating assembly comprises a tendon actuator member which is configured to be movable to at least pivot in one degree of freedom, and which includes a plurality of tendon engagement portions. Each engagement portion is drivingly couplable to at least one of the plurality of tendons. A drive mechanism is drivingly coupled to the actuator member so as to controllably pivot the actuator member in the at least one degree of freedom, so as to move at least one of the tendons relative to the shaft-like member so as to actuate the distal moveable member.
In another aspect, a minimally invasive surgical instrument comprises a shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end. A segmented wrist member comprises a plurality of spaced-apart segment vertebrae disposed sequentially adjacent to one another along a wrist longitudinal line. The plurality of vertebrae include a proximal vertebra connected to the shaft working end, a distal vertebra supporting an end effector, and at least one intermediate vertebra disposed between the proximal vertebra and the distal vertebra. The at least one intermediate vertebrae is connected to each adjacent vertebra by a pivotally movable segment coupling. Each segment coupling has a coupling axis nonparallel to the wrist longitudinal line. At least two of the coupling axes are non-parallel to one another. The movable segment couplings include at least one spring-like element arranged to regulate the pivotal motion of at least one adjacent vertebra. A plurality of movable tendon elements are disposed generally longitudinally with respect to the shaft and wrist member. The tendon elements each have a proximal portion, and a distal portion connected to the distal vertebra so as to pivotally actuate the distal vertebra. A tendon actuation mechanism is drivingly coupled to the tendons and configured to controllably move at least one of the plurality of tendons so as to pivotally actuate the plurality of connected vertebrae to laterally bend the wrist member with respect to the shaft.
Another aspect is directed a segment pivoted coupling mechanism for pivotally coupling two adjacent segment vertebrae of a multi-segment flexible member of a medical instrument, wherein the two adjacent segments have bending direction with respect to one another, and wherein the flexible member has at least one neutral bending axis. The instrument includes at least two movable actuation tendon passing through at least two apertures in each adjacent vertebrae, wherein the at least two apertures in each of the vertebra are spaced apart on opposite sides of the neutral axis with respect to the pivot direction, and wherein openings of the apertures are disposed one adjacent surfaces of the two vertebrae so as to generally define an aperture plane. The coupling mechanism comprises at least one inter-vertebral engagement element coupled to each of the vertebrae, the element pivotally engaging the vertebrae so as to define at least two spaced-apart parallel cooperating pivot axes, each one of the pivot axes being aligned generally within the aperture plane of a respective one of the adjacent vertebra, so as to provide that each vertebra is pivotally movable about its respective pivot axis, so as to balance the motion of the tendons on opposite sides of the neutral axis when the flexible member is deflected in the bending direction.